1. Field of the Invention
The present invention relates to the transporting, with an included rearrangement in order, of objects and particularly to the stacking or destacking of relatively fragile book blocks, books or like products. More specifically, this invention is directed to apparatus for altering the order of objects being conveyed between a pair of locations and especially to apparatus which either separates individual printing work products from previously formed stacks of such products, and thereafter conveys the separated products to a downstream utilization station, or receives a serial stream of such printing work products and rearranges the received products in stacks of preselected height. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for use in the continuous feeding, to a downstream distribution or utilization station, of individual printing works products such as book blocks, books and similar products. It is common practice in the art to form such printing work products into stacks for temporary storage. When further use of the thus stacked products is required, the products must be destacked and serially conveyed to a downstream work station. The previously available destacking methods and apparatus have had a number of inherent deficiencies including a comparatively high degree of mechanical complexity, and thus less than the desired reliability, relatively high cost and a relatively slow product throughput rate.
Published German patent application 28 04 781 discloses a book destacking method and apparatus in which stacked printing work products, after supply and acquisition, are moved vertically. The individual books are laterally ejected from the upwardly moving stack upon becoming the uppermost book in the stack and reaching the level of a discharge conveyor. The apparatus of this published German application comprises a lower supply conveyor belt, an upwardly extending paternoster with stack supports mounted thereon, a push-off device located above the paternoster and having push-off fingers, and an upper discharge conveyor. The push-off device supplies the individual books to the upper conveyor, for transport to the downstream utilization station, as they become the uppermost book in the stack as a result of the elevation of the stack supported on the paternoster.
Continuing to discuss the apparatus of German application DOS 28 04 781, the paternoster comprises a frame and chains which run in lateral guides. Cooperating pairs of bar-shaped supports are mounted on the chains at predetermined intervals with the supports of each pair facing one another. The spacing between the lateral guides for the chains may be adjusted to suit different book sizes through the use of spindles mounted in transversely oriented members of the frame.
The apparatus disclosed in German patent application DOS 28 04 781 is designed to destack books gently, so as to avoid damage thereto, and is intended especially for destacking books to which protective jackets have already been applied. The risk of damage to the books being destacked is minimized by acting upon the books from above during separation from the stack. However, the book destacking apparatus of the published German application is comparatively expensive, due to the need to provide a vertical transport system between the lower, entry conveyor and the upper, discharge conveyor. The inclusion of the vertical transport system also dictates a relatively complex mechanical design, which inherently diminishes reliability, and the recycling time of the vertical transport imposes an upper limit on book throughput rate.